Systems and methods for removal of duplicated packets for transmission

ABSTRACT

According to certain embodiments, a method in a wireless device includes transmitting a protocol data unit (PDU) or segment of a PDU on a first link and transmitting the PDU or the segment of the PDU on a second link. One or more retransmissions of the PDU or the segment of the PDU are scheduled on the second link. A positive acknowledgment is received from a receiver. The positive acknowledgement indicates a successful receipt of the PDU or the segment of the PDU on the first link. In response to receiving the positive acknowledgement, the one or more retransmissions of the PDU or the segment of the PDU on the second link are cancelled.

PRIORITY

This nonprovisional application is a U.S. National Stage Filing under 35U.S.C. § 371 of International Patent Application Serial No.PCT/EP2017/082577 filed Dec. 13, 2017, and entitled “Systems And MethodsFor Removal Of Duplicated Packets For Transmission” which claimspriority to U.S. Provisional Patent Application No. 62/476,505 filedMar. 24, 2017, both of which are hereby incorporated by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates, in general, to wireless communicationsand, more particularly, methods and systems for removal of duplicatedpackets for transmission.

BACKGROUND

In NR, Dual Connectivity (DC) in downlink (DL) and uplink (UL) are twoof the features which will be standardized. These features are alsoavailable in Long Term Evolution (LTE). In NR, the Packet DataConvergence Protocol (PDCP) data duplication will also be standardized.This means that the same PDCP protocol data unit (PDU) may betransmitted on two different legs/paths. This type of feature may beuseful in scenarios when reliability is important such as ultra-reliablelow latency communication (URLLC) limited-coverage situations.

FIG. 1 illustrates the DC architecture between LTE and NR. When dataduplication is enabled, the same PDCP PDU is transmitted by each radioaccess technology (RAT). When the radio link control (RLC) entityrequests data from PDCP, the PDCP layer delivers the PDCP PDU to therequesting RLC entity.

When RLC Acknowledge Mode (AM) is configured, each RLC entity willperform retransmissions until the data has been successfullyacknowledged or the maximum number of RLC retransmissions has beenreached. In the latter case, the UE triggers the Radio Link Failure(RLF) procedure. In limited-coverage situations, the maximum number ofRLC retransmissions may be reached.

When packet duplication is enabled, there may be cases when a PDCP PDUis received via one of the legs while the same (duplicated) PDCP PDU hasnot or has not yet been received by the other leg due to link problems.The RLC entity of the link with problems may be performing RLCretransmissions of the RLC PDU(s) containing the PDCP PDU. If the RLCentity reaches the maximum number of retransmissions, the DE willtrigger a RLF procedure though such a procedure is not really necessary.Further, triggering a RLF procedure may not be desirable when there is,at least, one link which is performing and in which data istransmitted/received correctly.

SUMMARY

To address the foregoing problems with existing solutions, disclosed ismethods and systems for removal of duplicated packets for transmission.Specifically, a mechanism is provided for removing radio link control(RLC) protocol data units (PDUs), which contained a certain Packet DataConvergence Protocol (PDCP) PDU, from the RLC buffer when the RLC PDU(s)are being transmitted or retransmitted to a receiver by on link thoughthe PDCP PDU was received by the receiver via a second link.

In certain embodiments, the systems and methods may be implemented in orby a wireless device, which may include a user equipment (UE), and/or anetwork node, which may include a eNodeB (eNB).

According to certain embodiments, a method in a wireless device mayinclude transmitting a PDU or segment of a PDU on a first link andtransmitting the PDU or the segment of the PDU on a second link. One ormore retransmissions of the PDU or the segment of the PDU are scheduledon the second link. A positive acknowledgment is received from areceiver. The positive acknowledgement indicates a successful receipt ofthe PDU or the segment of the PDU on the first link. In response toreceiving the positive acknowledgement, the one or more retransmissionsof the PDU or the segment of the PDU the second link are cancelled.

According to certain embodiments, a wireless device may includeprocessing circuitry configured to transmit a PDU or a segment of a PDUon a first link and transmit the PDU or the segment of the PDU on asecond link. One or more retransmissions of the PDU or the segment ofthe PDU are scheduled on the second link. A positive acknowledgment isreceived from a receiver. The positive acknowledgement indicates asuccessful receipt of the PDU or the segment of the PDU on the firstlink. In response to receiving the positive acknowledgement, the one ormore retransmissions of the PDU or the segment of the PDU on the secondlink are cancelled.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, certain embodiments may avoid theunnecessary triggering of a Radio Link Failure (RLF) procedure inresponse to a maximum number of RLC transmissions when data isduplicated and transmitted via two different links and a successfultransmission is received via one of the two links. Accordingly, certainembodiments save network resources. Additionally, certain embodimentsavoid RLC reestablishments.

Other advantages may be readily apparent to one having skill in the art.Certain embodiments may have none, some, or all of the recitedadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed embodiments and theirfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates the DC architecture between LTE and NR;

FIG. 2 illustrates an example wireless network for removal of duplicatedpackets for transmission, according to certain embodiments;

FIG. 3 illustrates an example wireless device for removal of duplicatedpackets for transmission, according to certain embodiments;

FIG. 4 illustrate an example network node for removal of duplicatedpackets for transmission, according to certain embodiments;

FIG. 5 illustrates example mapping of Packet Data Convergence Protocol(PDCP) Protocol Data Units (PDUs) to Radio Link Control (RLC) PDUs,according to certain embodiments;

FIG. 6 illustrates an example PDCP PDU transmitted independently by tworadio link control (RLC) entities, according to certain embodiments;

FIG. 7 illustrates an example transmission sequence chart for removal ofduplicate packets for transmission, according to certain embodiments;

FIG. 8 illustrates an example wireless network for the discarding ofpackets based on feedback transmitted on the X2 channel, according tocertain embodiments;

FIG. 9 illustrates an example method by a wireless device for removal ofduplicated packets for transmission, according to certain embodiments;

FIG. 10 illustrates an example method by a receiver for removal ofduplicated packets for transmission, according to certain embodiments;and

FIG. 11 illustrates an exemplary radio network controller or corenetwork node, according to certain embodiments.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure may provide methods andsystems for controlling gap sharing between intra-frequency measurementsof different types. Particular embodiments are described in FIGS. 2-15of the drawings, like numerals being used for like and correspondingparts of the various drawings.

FIG. 2 illustrates a wireless network 100 for removal of duplicatedpackets for transmission, in accordance with certain embodiments.Network 100 includes one or more wireless devices 110A-C, which may beinterchangeably referred to as wireless devices 110 or UEs 110, andnetwork nodes 115A-C, which may be interchangeably referred to asnetwork nodes 115 or eNodeBs 115. A wireless device 110 may communicatewith network nodes 115 over a wireless interface. For example, wirelessdevice 110A may transmit wireless signals to one or more of networknodes 115, and/or receive wireless signals from one or more of networknodes 115, The wireless signals may contain voice traffic, data traffic,control signals, and/or any other suitable information. In someembodiments, an area of wireless signal coverage associated with anetwork node 115 may be referred to as a cell. In some embodiments,wireless devices 110 may have D2D capability. Thus, wireless devices 110may be able to receive signals from and/or transmit signals directly toanother wireless device 110. For example, wireless device 110A may beable to receive signals from and/or transmit signals to wireless device110B.

In certain embodiments, network nodes 115 may interface with a radionetwork controller (not depicted in FIG. 2). The radio networkcontroller may control network nodes 115 and may provide certain radioresource management functions, mobility management functions, and/orother suitable functions. In certain embodiments, the functions of theradio network controller may be included in network node 115. The radionetwork controller may interface with a core network node. In certainembodiments, the radio network controller may interface with the corenetwork node via an interconnecting network. The interconnecting networkmay refer to any interconnecting system capable of transmitting audio,video, signals, data, messages, or any combination of the preceding. Theinterconnecting network may include all or a portion of a publicswitched telephone network (PSTN), a public or private data network, alocal area network (LAN), a metropolitan area network (MAN), a wide areanetwork (WAN), a local, regional, or global communication or computernetwork such as the Internet, a wireline or wireless network, anenterprise intranet, or any other suitable communication link, includingcombinations thereof.

In some embodiments, the core network node may manage the establishmentcommunication sessions and various other functionalities for wirelessdevices 110. Wireless devices 110 may exchange certain signals with thecore network node using the non-access stratum layer. In non-accessstratum signaling, signals between wireless devices 110 and the corenetwork node may be transparently passed through the radio accessnetwork. In certain embodiments, network nodes 115 may interface withone or more network nodes over an internode interface. For example,network nodes 115A and 115B may interface over an X2 interface.

As described above, example embodiments of network 100 may include oneor more wireless devices 110, and one or more different types of networknodes capable of communicating (directly or indirectly) with wirelessdevices 110. Wireless device 110 may refer to any type of wirelessdevice communicating with a node and/or with another wireless device ina cellular or mobile communication system. Examples of wireless device110 include a target device, a device-to-device (D2D) capable device, amachine type communication (MTC) device or other UE capable ofmachine-to-machine (M2M) communication, a mobile phone or otherterminal, a smart phone, a PDA (Personal Digital Assistant), a portablecomputer (e.g., laptop, tablet), a sensor, a modem, laptop embeddedequipment (LEE), laptop mounted equipment (LME), USB dangles, ProSe UE,V2V UE, V2X USE, MTC UE, eMTC UE, FeMTC UP, UP Cat 0, UE Cat M1,narrowband Internet of Things (NB-IoT) UE, UE Cat NB1, or another devicethat can provide wireless communication. A wireless device 110 may alsobe referred to as UE, a station (STA), a device, or a terminal in someembodiments. Also, in some embodiments, generic terminology, “radionetwork node” (or simply “network node”) is used. It can be any kind ofnetwork node, which may comprise a Node B, base station (BS),multi-standard radio (MSR) radio node such as MSR BS, eNode B, MeNB,SeNB, a network node belonging to MCG or SCG, network controller, radionetwork controller (RNC), base station controller (BSC), relay donornode controlling relay, base transceiver station (BTS), access point(AP), transmission points, transmission nodes, RRU, RRH, nodes indistributed antenna system (DAS), core network node (e.g. MSC, MMEetc.), O&M, OSS, SON, positioning node (e.g. E-SMLC), MDT, testequipment, or any suitable network node. Example embodiments of wirelessdevices 110, network nodes 115, and other network nodes (such as radionetwork controller or core network node) are described in more detailwith respect to FIGS. 3, 4, and 15, respectively.

Although FIG. 2 illustrates a particular arrangement of network 100, thepresent disclosure contemplates that the various embodiments describedherein may be applied to a variety of networks having any suitableconfiguration. For example, network 100 may include any suitable numberof wireless devices 110 and network nodes 115, as well as any additionalelements suitable to support communication between wireless devices orbetween a wireless device and another communication device (such as alandline telephone). Furthermore, although certain embodiments may bedescribed as implemented in a long term evolution (LTE) network, theembodiments may be implemented in any appropriate type oftelecommunication system supporting any suitable communication standardsand using any suitable components, and are applicable to any LTE basedsystems such as MTC, eMTC, and NB-IoT. As an example, MTC UE, eMTC UE,and NB-IoT UE may also be called UE category 0, UE category M1 and UEcategory NB1, respectively. However, the embodiments are applicable toany radio access technology (RAT) or multi-RAT systems in which thewireless device receives and/or transmits signals (e.g., data). Forexample, the various embodiments described herein may also be applicableto, LTE-Advanced, and LTE-U UMTS, LTE FDD/TDD, WCDMA/HSPA, GSM/GERAN,WiFi, WLAN, cdma2000, WiMax, 5G, New Radio (NR), another suitable radioaccess technology, or any suitable combination of one or more radioaccess technologies. It is noted that 5G, the fifth generation of mobiletelecommunications and wireless technology is not yet fully defined butin an advanced draft stage with 3GPP. It includes work on 5G New Radio(NR) Access Technology. LTE terminology is used herein in a forwardlooking sense, to include equivalent 5G entities or functionalitiesalthough a different term may be specified in 5G. A general descriptionof the agreements on 5G NR Access Technology is contained in most recentversions of the 3GPP 38-series Technical Reports. Although certainembodiments may be described in the context of wireless transmissions inthe downlink, the present disclosure contemplates that the variousembodiments are equally applicable in the uplink and vice versa. Thedescribed techniques are generally applicable for transmissions fromboth network nodes 115 and wireless devices 110.

FIG. 3 illustrates an example wireless device 110 for controlling gapsharing between intra-frequency measurements of different types, inaccordance with certain embodiments. As depicted, wireless device 210includes transceiver 210, processing circuitry 220, and memory 230. Insome embodiments, transceiver 210 facilitates transmitting wirelesssignals to and receiving wireless signals from network node 115 (e.g.,via an antenna), processing circuitry 220 executes instructions toprovide some or all of the functionality described above as beingprovided by wireless device 110, and memory 230 stores the instructionsexecuted by processing circuitry 220. Examples of a wireless device 110are provided above.

Processing circuitry 220 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of wireless device 110. In some embodiments, processingcircuitry 220 may include, for example, one or more computers, one ormore central processing units (CPUs), one or more processors, one ormore microprocessors, one or more applications, and/or other logic.

Memory 230 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by processing circuitry. Examples of memory230 include computer memory (for example, Random Access Memory (RAM) orRead Only Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information.

Other embodiments of wireless device 110 may include additionalcomponents beyond those shown in FIG. 3 that may be responsible forproviding certain aspects of the wireless device's functionality,including any of the functionality described above and/or any additionalfunctionality (including any functionality necessary to support thesolution described above).

FIG. 4 illustrate an example network node 115 for controlling gapsharing between intra-frequency measurements of different types,according to certain embodiments. As described above, network node 115may be any type of radio network node or any network node thatcommunicates with a wireless device and/or with another network node.Examples of a network node 115 are provided above.

Network nodes 115 may be deployed throughout network 100 as a homogenousdeployment, heterogeneous deployment, or mixed deployment. A homogeneousdeployment may generally describe a deployment made up of the same (orsimilar) type of network nodes 115 and/or similar coverage and cellsizes and inter-site distances. A heterogeneous deployment may generallydescribe deployments using a variety of types of network nodes 115having different cell sizes, transmit powers, capacities, and inter-sitedistances. For example, a heterogeneous deployment may include aplurality of low-power nodes placed throughout a macro-cell layout.Mixed deployments may include a mix of homogenous portions andheterogeneous portions.

Network node 115 may include one or more of transceiver 310, processingcircuitry 320, memory 330, and network interface 340. In someembodiments, transceiver 310 facilitates transmitting wireless signalsto and receiving wireless signals from wireless device 110 (e.g., via anantenna), processing circuitry 320 executes instructions to provide someor all of the functionality described above as being provided by anetwork node 115, memory 330 stores the instructions executed byprocessing circuitry 320, and network interface 340 communicates signalsto backend network components, such as a gateway, switch, router,Internet, Public Switched Telephone Network (PSTN), core network nodesor radio network controllers, etc.

In certain embodiments, network node 115 may be capable of usingmulti-antenna techniques, and may be equipped with multiple antennas andcapable of supporting MIMO techniques. The one or more antennas may havecontrollable polarization. In other words, each element may have twoco-located sub elements with different polarizations (e.g., 90 degreeseparation as in cross-polarization), so that different sets ofbeamforming, weights will give the emitted wave different polarization.

Processing circuitry 320 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of network node 115. In some embodiments, processing circuitry320 may include, for example, one or more computers, one or more centralprocessing units (CPUs), one or more microprocessors, one or moreapplications, and/or other logic.

Memory 330 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 330 includecomputer memory (for example, Random Access Memory (RAM) or Read OnlyMemory (ROM)), mass storage media (for example, a hard disk), removablestorage media (for example, a Compact Disk (CD) or a Digital Video Disk(DVD)), and/or or any other volatile or non-volatile, non-transitorycomputer-readable and/or computer-executable memory devices that storeinformation.

In some embodiments, network interface 340 is communicatively coupled toprocessing circuitry 320 and may refer to any suitable device operableto receive input for network node 115, send output from network node115, perform suitable processing of the input or output or both,communicate to other devices, or any combination of the preceding,Network interface 340 may include appropriate hardware (e.g., port,modem, network interface card, etc.) and software, including protocolconversion and data processing capabilities, to communicate through anetwork.

Other embodiments of network node 115 may include additional componentsbeyond those shown in FIG. 4 that may be responsible for providingcertain aspects of the radio network node's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). The various different types of network nodes mayinclude components having the same physical hardware but configured(e.g., via programming) to support different radio access technologies,or may represent partly or entirely different physical components.Additionally, the terms first and second are provided for examplepurposes only and may be interchanged.

According to certain embodiments, wireless devices 110 and network node115 may cooperate to result in the removal of duplicated packets fortransmission. For example, wireless device 110 may be configured bynetwork node 115 to remove duplicated packets from transmission whenconfigured for Radio link Control (RLC) Acknowledge Mode(AM)/Unacknowledge Mode (UM). According to certain embodiments, whenPacket Data Convergence Protocol (PDCP) Protocol Data Units (PDUs) aretransmitted via two links, the RLC entity of each of the links willtransmit the PDCP PDU. Each RLC entity will transmit the PDCP PDU in oneor more than one RLC PDU(s) or RLC PDU segments. FIG. 5 illustrates anexample mapping 400 of PDCP PDUs to RLC PDUs.

FIG. 6 illustrates a PDCP PDU 500 transmitted independently by two RLCentities, according to certain embodiments. Typically, the receivingentity may transmit a positive acknowledgment within a RLC status reportfor each RLC PDU that is successfully received. When all RLC PDUs (orPDU segments) carrying the different parts of the PDCP PDU have beenacknowledged, the RLC entity will indicate to the PDCP entity that thePDCP packet was received by the peer entity.

FIG. 7 illustrates an example transmission sequence 600 for removal ofduplicate packets for transmission when duplicate PDCP PDUs aretransmitted via two links. According to certain embodiments, when thePDCP entity 605 receives an indication by a first one of the RLCentities 610A that a certain PDCP PDU has been received by the peerentity:

-   -   1) The PDCP entity 605 indicates to the second RLC entity 610E        to stop the transmission of the RLC PDU(s) containing the PDCP        PDU.    -    According to certain embodiments, it may be assumed that the        second RLC entity 610B had not yet indicated that the PDCP PDU        was received by the peer entity. Thus the indication from PDCP        605 to this second RLC entity 610B may be optional, according to        certain embodiments, and only transmitted if this second RLC        entity 610B did not yet indicate successful transmission of the        PDCP PDU.    -    According to certain embodiments, the PDCP 605 and the second        RLC entity 610B may not be co-located. In such an embodiment,        communication of the indication to discard PDCP PDUs in the        second RLC may 610B be communicated via a backhaul channel. For        example, the indication may be communicated via the X2 (or        evolution thereof). According to a particular embodiment, the        indication may be included in flow control signaling from a node        implementing PDCP to a node implementing RLC. FIG. 8 illustrates        an example wireless network 700 for the discarding of packets        based on feedback transmitted on the X2 channel.    -   2) The second RLC entity 6108 should stop the transmissions of        the RLC PDU(s) mapping to the PDCP PDU. According to a        particular embodiment, for example, the second RLC entity 610B        may remove the PDCP PDU from the queuing buffer, which may        include an RLC SDU, and discard those RLC PDUs (or RLC PDU        segments). The second RLC entity may then update the RLC status        variables. For example, the second RLC entity 610B may move the        transmission window beyond those discarded PDUs when the second        RLC entity 610B considers the discarded PDUs as successfully        transmitted.    -    According to certain embodiments relating to AM transmissions,        the counter for transmission+retransmissions of the RLC PDU may        be reset so that for the particular RLC PDU, the indication of        the maximum number of retransmissions reached, cannot be        reached.    -   3) According to certain embodiments, the second RLC entity 610B        may inform the peer RLC entity (receiving RLC entity 615B) of        which RLC PDU(s) should be discarded. In a particular        embodiment, transmission of this indication (“RLC control PDU”)        may be prioritized over other RLC data to be transmitted.    -    It may be recognized that the step of the second RLC entity        610B informing the peer RLC entity 615B of which RLC PDU(s) to        discard may be difficult since it may be assumed that the link        is broken. However, such information allows the receiver to move        the reception window beyond the discarded PDUs. According to        certain embodiments, the reordering timer does not affect the        delivery to PDCP and, thus, does not present a big issue, but        may lead to status report transmission.    -    According to certain embodiments, it may be assumed that the        link over this second RLC 610B is eventually again available for        transmission, so that the receiver side can indeed be informed        of discarded PDUs. When this link is available for transmission        again, due to the earlier discard, already received data via the        other RLC, does not need to be retransmitted redundantly via the        second RLC 610B anymore.    -   4) The peer RLC entity (receiving RLC entity 615B) of this        second RLC 610B discards the RLC PDU(s) indicated in this        received indication from the transmitting RLC 610B and updates        the RLC status variables and timers accordingly (e.g. reordering        timer). The peer RLC entity 610B would consider these RLC PDUs        as “successfully received” PDUs, and move the reception window        beyond these PDUs.

According to certain embodiments, a PDCP transmission timeout RLF may beprovided. Specifically, to avoid the maximum number of RLCretransmissions indication being reached and the triggering of a RLFprocedure, an operator may choose to deactivate the indication for bothRLCs. To compensate and to still be able to reliably detect RLF, amethod PDCP can be considered. For example, according to certainembodiments, a maximum transmission time limit to acknowledge may bedefined for each PDCP PDU. If the maximum transmission time limit isreached, an indication may be triggered to higher layers, which thentrigger RLF. In a particular embodiment, when an RLC ACK for the PDCPPDU is received from either RLC 610A-B, the timer may be reset and RLFmay not be triggered. Alternatively, a single timer can be defined forthe PDCP lower transmit window edge. For example, the PDCP PDU with thelowest SN may not be acknowledged. When this PDCP PDU is notacknowledged for a certain time, the RLF indication is triggered tohigher layers.

FIG. 9 illustrates an example method 800 by a wireless device forremoval of duplicated packets for transmission, according to certainembodiments. In certain embodiments, the method may be performed by aPDCP layer of wireless device 110.

The method may begin at an step 802 when data is transmitted on a firstlink. In a particular embodiment, the data may include a PDCP PDU. Inanother embodiment, the data may include a PDCP PDU segment. The datamay be further transmitted on a second link, at step 804. Thus, firstand second copies of the data may be transmitted on first and secondlinks, respectively, in steps 802 and 804.

In a particular embodiment, the transmission on the first link isperformed by a first RLC entity of the wireless device 110 and thetransmission on the second link is performed by a second RLC entity ofthe wireless device 110. In a particular embodiment, the first linkand/or first RLC entity may be associated with a first radio accesstechnology and the second link and/or second RLC entity may beassociated with a second radio access technology.

At step 806, one or more additional retransmissions of the data arescheduled on the second link. In a particular embodiment, scheduling theat least one additional retransmission of the data may include storing aplurality of copies of the data as PDUs in a RLC SDU buffer.

At step 808, a positive acknowledgement indicating a successful receiptof the protocol data unit on the first link is received from thereceiver. In a particular embodiment, the positive acknowledgement isreceived in an RLC status report. In a particular embodiment, thepositive acknowledgement is received via a first RLC entity associatedwith wireless device 110. The first RLC entity may, thereafter transmitan indication to a PDCP entity of wireless device 110 that identifiesthat the data was successfully received by the receiver. Where thesecond RLC entity associated with the second link is not co-located withthe PDCP, such an indication may be transmitted and received via abackhaul channel, in a particular embodiment. In a particularembodiment, the second RLC entity may transmit an indication to areceiver side RLC entity on the second link. The indication may identifyone or more retransmissions of the data to be discarded.

In a particular embodiment, a maximum transmission time threshold may bedefined for receiving the positive acknowledgment. The maximumtransmission time threshold triggering a radio layer failure procedure.According to certain embodiments, a timer associated with the maximumtransmission time threshold may be reset in response to receiving thepositive acknowledgment to prevent triggering of the RLF procedure.

At step 810, in response to receiving the positive acknowledgement, theone or more additional retransmissions of the data on the second linkare cancelled. In a particular embodiment, where copies of the data arestored for retransmission in the RLC SDU buffer, the copies of the datamay be removed from the RLC SDU buffer and discarded.

FIG. 10 illustrates an example method 900 by a receiver for removal ofduplicated packets, according to certain embodiments. In certainembodiments, the method may be performed by a PDCP layer of thereceiver. In various particular embodiments, the receiver may include awireless device, which may include a UE. In another embodiment, thereceiver may include a network node.

The method may begin at an step 902 when the receiver receives, from awireless device 110, a PDU or segment of a PDU on a first link. In aparticular embodiment, the PDU or the segment of the PDU may be receivedby a first RLC entity 615A of the receiver from a first RLC entity 610Aof the wireless At step 904, in response to receiving the PDU or thesegment of the PDU on the first link, the receiver transmits a positiveacknowledgment to the wireless device. In a particular embodiment, thepositive acknowledgement may be transmitted in a radio link control,RLC, status report. In a particular embodiment, where the PDU or segmentof the PDU is received by a first RLC entity 615A of the receiver, thepositive acknowledgment may be transmitted by the first RLC entity 615Aof the receiver to a first RLC entity 610A of the wireless device.

At step 906, the receiver receives, from the wireless device, at leastone retransmission of the PDU or the segment of the PDU on a secondlink. In a particular embodiment, the first link may be associated witha first radio access technology and the second link is associated with asecond radio access technology. In a particular embodiment, the PDU orthe segment of the PDU may be received by a second RLC entity 615B ofthe receiver from a second RLC entity 610A of the wireless device. In aparticular embodiment, the receiver may store the PDU or the segment ofthe PDU in a RLC SDU buffer.

According to certain embodiments, the receiver may also receive, fromthe wireless device, a first indication identifying that the at leastone retransmission of the PDU or the segment of the PDU received on thesecond link should be discarded. The receiver may then discard the atleast one retransmission of the PDU or the segment of the PDU that wasreceived on the second link. For example, in a particular embodiment,the receiver may remove the PDU or the segment of the PDU from the RLCSDU buffet.

FIG. 11 illustrates an exemplary radio network controller or corenetwork node 1400, in accordance with certain embodiments. Examples ofnetwork nodes can include a mobile switching center (MSC), a servingGPRS support node (SGSN), a mobility management entity (MME), a radionetwork controller (RNC), a base station controller (BSC), and so on.The radio network controller or core network node 1000 includesprocessing circuitry 1020, memory 1030, and network interface 1040. Insome embodiments, processing circuitry 1020 executes instructions toprovide some or all of the functionality described above as beingprovided by the network node, memory 1030 stores the instructionsexecuted by processing circuitry 1020, and network interface 1040communicates signals to any suitable node, such as a gateway, switch,router, Internet, Public Switched Telephone Network (PSTN) network nodes115, radio network controllers or core network nodes 1000, etc.

Processing circuitry 1020 may include any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of the radio network controller or core network node 1000. Insome embodiments, processing circuitry 1020 may include, for example,one or more computers, one or more central processing units (CPUs), oneor more microprocessors, one or more applications, and/or other logic.

Memory 1030 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 1030include computer memory (for example, Random Access Memory (RAM) or ReadOnly Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information.

In some embodiments, network interface 1040 is communicatively coupledto processing circuitry 1020 and may refer to any suitable deviceoperable to receive input for the network node, send output from thenetwork node, perform suitable processing of the input or output orboth, communicate to other devices, or any combination of the preceding.Network interface 1040 may include appropriate hardware port, modem,network interface card, etc.) and software, including protocolconversion and data processing capabilities, to communicate through anetwork.

Other embodiments of the network node may include additional componentsbeyond those shown in FIG. 11 that may be responsible for providingcertain aspects of the network node's functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the solution describedabove).

According to certain embodiments, duplication in UL in dual connectivityis provided. Accordingly, several aspects of UL data duplication forDual Connectivity such as configuration, activation/deactivation, anddata duplication operation are discussed.

Data duplication may be more useful for ultra-reliable devices andservices. However, UL user plane data duplication might also be aninteresting option to cope with situations in which radio links are notstable, e.g. coverage limited situations, while trying to sustain thecertain UL bit rate. It could also be an option to help to achieve the 0ms interruption time requirement.

There are different options to activate deactivate this feature:

-   -   RRC message: The RRC message configuring the feature could        activate/deactivate the feature.    -   Event trigger: This mechanism could be similar as a measurement        event. Upon a certain event (configured by the network), the UE        would activate/deactivate the PDCP data duplication.    -   PDCP: PDCP layer could activate and deactivate duplication by        means of a PDCP control command. In this case, the NW could send        a PDCP control command to the UE when it wants to activate or        deactivate duplication. It is to be noted, that the        configuration should still be transmitted previously over RRC.    -   MAC: MAC already has MAC CE which enables the NW to modify        certain MAC features. MAC CE could be used to activate or        deactivate PDPC duplication; however, it creates an inter-layer        dependency which is not considered beneficial in this case.        Duplication of UL PDCP PDUs will take a considerable amount of        resources in the network and, therefore, activation/deactivation        should be fully in control of the network. From this angle, the        beat alternatives to control this feature may be RRC or PDCP.        According to certain embodiments:    -   PDCP Control Command can activate deactivate UL (DRB) data        duplication.    -   Once an PDCP duplication has been activated, the UE should        deliver the same PDCP PDUs to both RLC entities.    -   Once an PDCP duplication has been deactivated, the UE should not        deliver the same PDCP PDUs to both RLC entitles.    -   Any (duplicated) data in (RLC/MAC) lower layers should be        unaffected by the PDCP duplication activation/deactivation.

There may be situations in which, after duplication is activated, datain one of the legs does not go through due to e.g. bad radio conditions.The other leg, however, may perform adequately. That results in thatdata is received in the NW through one of the legs.

In the leg which had bad radio, the RLC will be performingretransmissions which might not be longer needed (as it has beenreceived through the other leg), if the leg recovers, the RLC may stilltransmit the data pending in the RLC/MAC (i.e. the retransmissions). Allthis data, however, will be discarded by the NW. Thus, it is preferableif the UE does not transmit it.

In the worst cases, if this leg does not recover, the maximum number ofRLC retransmissions could be reached, and this would trigger an RLFfailure, which might not be needed in this case.

This opens up the question on whether a mechanism should be introducedto avoid wasting resources and avoid RLFs for duplicated data which hasbeen received in one leg hut may be under retransmissions in the secondleg.

The PDCP layer at the UE can know if a PDCP PDU was received by the NWif RLC AM was used. The PDCP layer also knows in which leg the data wassuccessfully received. Thus, The PDCP entity could indicate to the otherRLC entity to stop the transmission of those PDCP PDUs. The peer entity(at the NW side) would also need to be informed of this, so that thereceiver window can be moved forward.

According to certain embodiments, a method in a wireless device mayinclude:

-   -   transmitting data on a first link;    -   transmitting the data on a second link;    -   scheduling one or more additional retransmissions of the data on        the second link;    -   receiving, from a receiver, a positive acknowledgement        indicating a successful receipt of the protocol data unit on the        first link; and    -   in response to receiving the positive acknowledgement,        cancelling the one or more additional retransmissions of the        data on the second link;    -   optionally, the data comprises a packet data unit;    -   optionally, the data comprises a segment of a packet data unit;    -   optionally, the positive acknowledgement is received in an RLC        status report;    -   optionally, the positive acknowledgement is received via a first        RLC entity associated with the first link, and wherein the first        RLC entity transmits an indication to a PDCP entity of the        wireless device that the data was received by the receiver;    -   optionally, a second RLC entity associated with the second link        is not co-located with the PDCP and the indication transmitted        to the PDCP entity is received via a backhaul channel;    -   optionally, the second RLC entity transmits an indication to the        a receiver side RLC entity associated with the second link, the        indication identifying one or more retransmissions of the data        to be discarded;    -   optionally, scheduling the at least one additional        retransmission of the data comprises storing a plurality of        copies of the data as PDUs in a RLC SDU buffer;    -   optionally, cancelling the one or more additional        retransmissions of the data on the second link comprises        removing the plurality of copies of the data from the RLC SDU        buffer and discarding the removed copies of the data;    -   optionally, the positive acknowledgement received via the first        RLC entity associated with the first link is received before a        positive acknowledgement is received via a second RLC entity        associated with the second link;    -   optionally, the first link is associated with a first radio        access technology and the second link is associated with a        second radio access technology;    -   optionally, the method is performed by a PDCP layer of the        wireless device;    -   optionally, the transmission on the first link is performed by a        first RLC entity of the wireless device;    -   optionally, the transmission on the second link is performed by        a second RLC entity of the wireless device;    -   optionally, receiving a configuration from a network node for        RLC acknowledgement mode (AM);    -   optionally, a maximum transmission time threshold is defined for        receiving the positive acknowledgment, the maximum transmission        time threshold triggering a radio layer failure procedure;    -   optionally, in response to receiving the positive        acknowledgment, resetting a timer associated with the maximum        transmission time threshold to prevent triggering of the RLF        procedure.

According to certain embodiments, a wireless device may include:

-   -   processing circuitry, the processing circuitry configured to:        -   transmit data on a first link;        -   transmit the data on a second link;        -   schedule one or more additional retransmissions of the data            on the second link;        -   receive, from a receiver, a positive acknowledgement            indicating a successful receipt of the protocol data unit on            the first link; and        -   in response to receiving the positive acknowledgement,            cancel the one or more additional retransmissions of the            data on the second link;    -   optionally, the data comprises a packet data unit;    -   optionally, the data comprises a segment of a packet data unit;    -   optionally, the positive acknowledgement is received in an RLC        status report;    -   optionally, the positive acknowledgement is received via a first        RLC entity associated with the first link, and wherein the first        RLC entity transmits an indication to a PDCP entity of the        wireless device that the data was received by the receiver;    -   optionally, a second RLC entity associated with the second link        is not co-located with the PDCP and the indication transmitted        to the PDCP entity is received via a backhaul channel;    -   optionally, the second RLC entity transmits an indication to the        a receiver side RLC entity associated with the second link, the        indication identifying one or more retransmissions of the data        to be discarded;    -   optionally, scheduling the at least one additional        retransmission of the data comprises storing a plurality of        copies of the data as PDUs in a RLC SDU buffer;    -   optionally, cancelling the one or more additional        retransmissions of the data on the second link comprises        removing the plurality of copies of the data from the RLC SDU        buffer and discarding the removed copies of the data;    -   optionally, the positive acknowledgement received via the first        RLC entity associated with the first link is received before a        positive acknowledgement is received via a second RLC entity        associated with the second link;    -   optionally, the first link is associated with a first radio        access technology and the second link is associated with a        second radio access technology;    -   optionally, the processing circuitry is associated with a PDCP        layer of the wireless device;    -   optionally, transmission on the first link is performed by a        first RLC entity of the wireless device;    -   optionally, transmission on the second link is performed by a        second RLC entity of the wireless device;    -   optionally, the processing circuitry is further configured to        receive a configuration from a network node for RLC        acknowledgement mode (AM);    -   optionally, a maximum transmission time threshold is defined for        receiving the positive acknowledgment, the maximum transmission        time threshold triggering a radio layer failure procedure;    -   optionally, in response to receiving the positive        acknowledgment, the processing circuitry is further configured        to reset a timer associated with the maximum transmission time        threshold to prevent triggering of the RLF procedure.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, certain embodiments may avoid theunnecessary triggering of a Radio Link Failure (RLF) procedure inresponse to a maximum number of RLC transmissions when data isduplicated and transmitted via two different links and a successfultransmission is received via one of the two links. Accordingly, certainembodiments save network resources. Additionally, certain embodimentsavoid RLC reestablishments.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of thedisclosure. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic. As used in this document, “each” refers to each member of a setor each member of a subset of a set.

Modifications, additions, or omissions may be made to the methodsdescribed herein without departing from the scope of the disclosure. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. Accordingly, the above descriptionof the embodiments does not constrain this disclosure. Other changes,substitutions, and alterations are possible without departing from thespirit and scope of this disclosure, as defined by the following claims.

The invention claimed is:
 1. A method in a network node comprises:transmitting, by a first radio link control (RLC) entity, a Packet DataConvergence Protocol (PDCP) protocol data unit (PDU) or segment of aPDCP PDU on a first link; transmitting, by a second RLC entity, the PDCPPDU or the segment of the PDCP PDU on a second link, wherein the secondRLC entity is associated with the second link; scheduling, by the secondRLC entity, one or more retransmissions of the PDCP PDU or the segmentof the PDCP PDU on the second link; receiving, from a receiver and viathe first RLC entity, a positive acknowledgement indicating a successfulreceipt of the PDCP PDU or the segment of the PDCP PDU on the firstlink; transmitting, by the first RLC entity an indication to a PDCPentity that the PDCP PDU or segment of the PDCP PDU was received by thereceiver; communicating, via a backhaul channel, an indication to thesecond RLC entity to discard the PDCP PDU or segment of the PDCP PDU,wherein the PDCP entity is not co-located with the second RLC entity;and in response to receiving the indication to discard the PDCP PDU orsegment of the PDCP PDU, cancelling the one or more retransmissions ofthe PDCP PDU or the segment of the PDCP PDU on the second link.
 2. Themethod of claim 1, wherein the positive acknowledgement is received in aRLC status report.
 3. The method of claim 1, wherein the positiveacknowledgment received via the first RLC entity associated with thefirst link is received before a positive acknowledgment is received viathe second RLC entity associated with the second link.
 4. The method ofclaim 3, wherein the second RLC entity transmits an indication to areceiver side RLC entity associated with the second link, the indicationidentifying one or more retransmissions of the data to be discarded. 5.The method of claim 1, wherein scheduling the at least oneretransmission of the PDCP PDU or the segment of the PDCP PDU comprisesstoring a plurality of copies of the PDCP PDU or the segment of the PDCPPDU in a RLC service data unit, SDU, buffer.
 6. The method of claim 5,wherein cancelling the one or more retransmissions of the PDCP PDU orthe segment of the PDCP PDU on the second link comprises removing theplurality of copies of the PDCP PDU or the segment of the PDCP PDU fromthe RLC SDU buffer and discarding the removed plurality of copies of thePDCP PDU or the segment of the PDCP PDU.
 7. The method of claim 1,wherein the first link is associated with a first radio accesstechnology and the second link is associated with a second radio accesstechnology.
 8. The method of claim 1, wherein a maximum transmissiontime threshold is defined for receiving the positive acknowledgment, themaximum transmission time threshold triggering a radio layer failure,RLF, procedure.
 9. The method of claim 8, further comprising, inresponse to receiving the positive acknowledgment, resetting a timerassociated with the maximum transmission time threshold to preventtriggering of the RLF procedure.
 10. A network node comprises:processing circuitry configured to: transmit, by a first Radio LinkControl (RLC) entity, a Packet Data Convergence Protocol (PDCP) protocoldata unit (PDU) or a segment of a PDCP PDU on a first link, wherein thefirst RLC entity is associated with the first link; transmit, by asecond RLC entity, the PDCP PDU or the segment of the PDCP PDU on asecond link, wherein the second RLC entity is associated with the secondlink; schedule one or more retransmissions of the PDCP PDU or thesegment of the PDCP PDU on the second link; receive, from a receiver andvia the first RLC entity, a positive acknowledgement indicating asuccessful receipt of the PDCP PDU or the segment of the PDCP PDU on thefirst link; transmit, by the first RLC entity an indication to a PDCPentity that the PDCP PDU or segment of the PDCP PDU was received by thereceiver; communicate, via a backhaul channel, an indication to thesecond RLC entity to discard the PDCP PDU or segment of the PDCP PDU,wherein the PDCP entity is not co-located with the second RLC entity;and in response to receiving the indication to discard the PDCP PDU orsegment of the PDCP PDU, cancel the one or more retransmissions of thePDCP PDU or the segment of the PDCP PDU on the second link.
 11. Thenetwork node of claim 10, wherein the positive acknowledgement isreceived in a RLC status report.
 12. The network node of claim 10,wherein the positive acknowledgment received via the first RLC entityassociated with the first link is received before a positiveacknowledgment is received via a second RLC entity associated with thesecond link.
 13. The network node of claim 12, wherein the second RLCentity transmits an indication to a receiver side RLC entity associatedwith the second link, the indication identifying one or moreretransmissions of the data to be discarded.
 14. The network node ofclaim 10, wherein scheduling the at least one retransmission of the PDCPPDU or the segment of the PDCP PDU comprises storing a plurality ofcopies of the PDCP PDU or the segment of the PDCP PDU in a RLC servicedata unit, SDU, buffer.
 15. The network node of claim 14, whereincancelling the one or more retransmissions of the PDCP PDU or thesegment of the PDCP PDU on the second link comprises removing theplurality of copies of the PDCP PDU or the segment of the PDCP PDU fromthe RLC SDU buffer and discarding the removed plurality of copies of thePDCP PDU or the segment of the PDCP PDU.
 16. The network node of claim10, wherein the first link is associated with a first radio accesstechnology and the second link is associated with a second radio accesstechnology.
 17. The network node of claim 10, wherein the processingcircuitry is associated with a PDCP layer of the network node.
 18. Thenetwork node of claim 10, wherein a maximum transmission time thresholdis defined for receiving the positive acknowledgment, the maximumtransmission time threshold triggering a radio layer failure, RLF,procedure.